This invention relates generally to aircraft navigation, and more specifically, to methods and systems for sensing aircraft airspeed.
Airspeed measurement is utilized as a navigation aid, a landing aid, and for fuel usage optimization in aircraft of all types. Typically, pressure sensors are utilized to provide the measurements from which airspeed can be calculated. For example, airspeed is calculated from the differential measurement of an impact pressure measured at a pitot port of the aircraft having a pressure sensor mounted within, and a static pressure measured at a static port of the aircraft also having a pressure sensor mounted within.
The above described pressure sensors are typically diaphragm type pressure sensors where pressure changes cause changes in the mechanical displacement of the diaphragms. These displacement changes are then sensed electronically, for example, through measurement of a resistive or capacitive change. The resistive or capacitive change is then converted to a value indicative of a pressure for both the pitot port and the static port. The pressure differential between the ports is then converted to airspeed data that is either displayed through a mechanical readout or by a processor which causes the airspeed to be displayed. Typically in such applications, a temperature sensor is also incorporated to compensate for temperature induced errors as changes in temperature affect operation of the above described pressure sensors.
Diaphragm type pressure sensors are large, costly, and inaccurate at low airspeeds. As such, diaphragm type pressure sensors are not practical in certain applications where measurements of airspeed are desired, for example, for small remotely piloted vehicles.